/* ifaddrs.h -- declarations for getting network interface addresses 
   Copyright (C) 2002 Free Software Foundation, Inc. 
   This file is part of the GNU C Library. 
   
   The GNU C Library is free software; you can redistribute it and/or 
   modify it under the terms of the GNU Lesser General Public 
   License as published by the Free Software Foundation; either 
   version 2.1 of the License, or (at your option) any later version. 
   
   The GNU C Library is distributed in the hope that it will be useful, 
   but WITHOUT ANY WARRANTY; without even the implied warranty of 
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 
   Lesser General Public License for more details. 
   
   You should have received a copy of the GNU Lesser General Public 
   License along with the GNU C Library; if not, write to the Free 
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 
   02111-1307 USA. */ 
 
#ifndef _IFADDRS_H 
#define _IFADDRS_H 1 
 
#include <features.h> 
#include <sys/socket.h> 
 
__BEGIN_DECLS 
 
/* The `getifaddrs' function generates a linked list of these structures. 
   Each element of the list describes one network interface. */ 
struct ifaddrs 
{ 
  struct ifaddrs *ifa_next; /* Pointer to the next structure. */ 
  
  char *ifa_name; /* Name of this network interface. */ 
  unsigned int ifa_flags; /* Flags as from SIOCGIFFLAGS ioctl. */ 
  
  struct sockaddr *ifa_addr; /* Network address of this interface. */ 
  struct sockaddr *ifa_netmask; /* Netmask of this interface. */ 
  union 
  { 
    /* At most one of the following two is valid. If the IFF_BROADCAST 
       bit is set in `ifa_flags', then `ifa_broadaddr' is valid. If the 
       IFF_POINTOPOINT bit is set, then `ifa_dstaddr' is valid. 
       It is never the case that both these bits are set at once. */ 
    struct sockaddr *ifu_broadaddr; /* Broadcast address of this interface. */ 
    struct sockaddr *ifu_dstaddr; /* Point-to-point destination address. */ 
  } ifa_ifu; 
  /* These very same macros are defined by <net/if.h> for `struct ifaddr'. 
     So if they are defined already, the existing definitions will be fine. */ 
# ifndef ifa_broadaddr 
# define ifa_broadaddr ifa_ifu.ifu_broadaddr 
# endif 
# ifndef ifa_dstaddr 
# define ifa_dstaddr ifa_ifu.ifu_dstaddr 
# endif 
 
  void *ifa_data; /* Address-specific data (may be unused). */ 
}; 
 
 
/* Create a linked list of `struct ifaddrs' structures, one for each 
   network interface on the host machine. If successful, store the 
   list in *IFAP and return 0. On errors, return -1 and set `errno'. 
   
   The storage returned in *IFAP is allocated dynamically and can 
   only be properly freed by passing it to `freeifaddrs'. */ 
extern int getifaddrs (struct ifaddrs **__ifap); 
 
/* Reclaim the storage allocated by a previous `getifaddrs' call. */ 
extern void freeifaddrs (struct ifaddrs *__ifa); 
 
__END_DECLS 
 
#endif /* ifaddrs.h */ 
